a well-known property of normal Fermi liquids [1]}, [2]}.
We are thus led to conclude, in full agreement with the zero-temperature calculations of the quasiparticle energy
and lifetime performed in Refs. [3]}, [4]}, that doped graphene sheets are normal Fermi liquids. Note that the fact that interactions enhance the quasiparticle velocity [see Eq. (REF )] implies that the specific heat of doped graphene sheets is suppressed with respect to its noninteracting value.
